The present invention relates to a yarn brake, especially, a yarn brake for a two-for-one twisting spindle or a two-for-one twisting spindle machine, having a substantially tube-shaped yarn brake housing in which a capsule-shaped brake cartridge is arranged, the brake cartridge comprising first and second telescopically movable tube portions which are movable against the bias of springs. Each tube portion of the brake cartridge has a substantially ball or curve shaped end portion with the pair of end portions disposed oppositely one another for each cooperating with a respective fixed axial position brake and/or a resiliently biased, axially movable brake ring with the pair of brake rings being at an adjustable axial spacing from one another.
Particularly in connection with the use of two-for-one twisting spindles, yarn brakes are known which comprise a yarn brake housing through which the yarn is axially trained. The inlet and outlet openings of the actual yarn brake region are respectively formed by brake rings having conical braking surfaces. The brake rings are typically comprised of a material having a high wear resistance. A brake cartridge, which forms the actual braking mechanism, extends between the individual inlet and outlet side of the brake rings and comprises two substantially cylindrical tube portions which are telescopically inserted into one another, and which include ball or curve shaped ends. The tubes enclose a spring which, upon the disposition of the brake cartridge in the yarn brake housing, outwardly resiliently biases the two tube end portions such that the curved-shaped ends of the tube portions are biased toward the brake rings and together therewith, as a function of the respective axial positions of the brake rings, exert the required braking force on the yarn traveling through the yarn brake. In accordance with the size of the required braking force, correspondingly stronger or weaker springs are disposed in the brake cartridge.
It is also conventionally known as well in connection with capsule yarn brakes that the actual braking body can be comprised of two tube sections, as is disclosed in German Industrial Model Patent Document 19 75 652, to provide a radially inwardly projecting flange portion on the inner end of the outermost tube section and a radially outwardly directed flange portion on the inner end of the innermost tube section so as to prevent or hinder an inadvertent release of the tube sections which are inserted into one another.
To permit adjustment or, respectively, setting of the braking force, it is known from DE 43 43 458 C2 (corresponding to U.S. Pat. No. 5,581,988) and DE 44 08 262 C2 (corresponding to U.S. Pat. No. 5,487,263), to set the axial position of the upper brake ring or, respectively, the brake ring carrier which supports this brake ring, in selected different settings so as to thereby vary the axial spacing of the upper and lower brake rings from one another. In the yarn brake disclosed in DE 43 43 458 C2, the lower brake ring is disposed in a fixed axial setting in the yarn brake housing while the upper brake ring is axially adjustably mounted in the yarn brake housing to thereby effect adjustment of the braking force. DE 44 08 262 C2 further discloses that the lower brake ring or, respectively, its brake ring carrier, can be adjusted relatively against the force of a return position spring by means of a downward pressure exerted from the direction of the upper brake ring, so that the downwardly moving brake cartridge, which is urged downwardly under the influence of gravity, can be supported against support elements which project radially inwardly from the inner wall of the yarn brake housing. The brake cartridge thereby loses contact with the upper and lower brake rings so that a training or feeding of the yarn through the yarn brake is possible.
It is additionally known in connection with two-for-one twisting spindles to arrange two brake cartridges in serial arrangement with one another in tandem manner so that, in total, four braking locations are available. A yarn brake of this configuration with one after another tandem brake cartridges has a fairly long axial extent.
It is an object of the present invention to provide simple and effective possibilities for altering the braking force.
In accordance with the present invention, a yarn brake is provided having the two tube sections as well as a third tube section added to the brake cartridge such that the three tube section are telescopically arranged for axial movement relative to one another against a spring force. The yarn brake of the present invention is characterized substantially in that, instead of a two piece brake cartridge, now a three piece brake cartridge is comprised together into a unit, whereby, for example, in contrast to a tandem-type, one after another serially activated brake cylinder, significant material and space savings can be realized.
In accordance with a preferred embodiment of the yarn brake of the present invention, it is provided that the yarn brake includes a guide conduit which communicates with its yarn brake housing, the yarn guide conduit receiving therein an axially adjustably positionable yarn intake tube adjustable to at least two positions relative to the guide conduit and having an inner end which supports the third brake ring thereon. By adjustment of the axial position of the yarn intake tube, one can, as desired, adjust the third brake ring relative to the third brake surface, so that this third brake surface can be rendered inoperable. By lowering of the yarn intake tube, the braking action of the third brake surface can be put into operation and this, in fact, in addition to the possibilities which are offered by positional adjustment of the first or the second brake ring carriers.